Mersenne.java Source code

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Here is the source code for Mersenne.java

Source

/*
 * @(#)Mersenne.java   1.0 Apr 26, 2008
 *
 *   The MIT License
 *
 *   Copyright (c) 2008 Malachi de AElfweald <malachid@gmail.com>
 *
 *   Permission is hereby granted, free of charge, to any person obtaining a copy
 *   of this software and associated documentation files (the "Software"), to deal
 *   in the Software without restriction, including without limitation the rights
 *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 *   copies of the Software, and to permit persons to whom the Software is
 *   furnished to do so, subject to the following conditions:
 *
 *   The above copyright notice and this permission notice shall be included in
 *   all copies or substantial portions of the Software.
 *
 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 *   THE SOFTWARE.
 */
//package org.eoti.math.prime;

import java.math.BigInteger;
import java.util.*;

public class Mersenne {
    protected static BigInteger two = BigInteger.valueOf(2);
    protected static String[] primes = new String[] { "2", "3", "5", "7", "13", "17", "19", "31", "61", "89", "107",
            "127", "521", "607", // M1-M14
            "1279", "2203", "2281", "3217", "4253", "4423", "9689", "9941", "11213", "19937", // M15-M23
            "21701", "23209", "44497", "86243", "110503", "132049", "216091", "756839", // M24-M32
            "859433", "1257787", "1398269", "2976221", "3021377", "6972593", "13466917", // M33-M39
            // indexes of rest could be wrong
            "20996011", "24036583", "25964951", "30402457", "32582657", "37156667", // M40-M45???
            "42643801", "43112609" // M46-M47???
    };

    protected BigInteger value;
    protected int index;

    public Mersenne(int index) {
        this.index = index;
        value = two.pow(Integer.parseInt(primes[index - 1]));
        value = value.subtract(BigInteger.ONE);
    }

    // Per common Mersenne Prime tables, index is 1-based
    public int getIndex() {
        return index;
    }

    public Integer getN() {
        return Integer.parseInt(primes[index - 1]);
    }

    public Integer getBitLength() {
        return getN();
    }

    public Integer getDigitLength() {
        return ("" + getValue()).length();
    }

    public BigInteger getValue() {
        return value;
    }

    public static Iterable<Mersenne> iterator() {
        return new Iterable<Mersenne>() {
            public Iterator<Mersenne> iterator() {
                return new MersenneIter();
            }
        };
    }

    static class MersenneIter implements Iterator<Mersenne> {
        protected int currIndex = 0;

        MersenneIter() {
        }

        public boolean hasNext() {
            return currIndex <= primes.length;
        }

        public Mersenne next() {
            return new Mersenne(++currIndex);
        }

        public void remove() {
            throw new UnsupportedOperationException("Remove not implemented");
        }
    }
}